The message read: "We are devastated about the recent cancer diagnosis of our oldest son Noah, who is currently undergoing treatment in the US.

"We have always been very vocal about the importance of family and the love we have for our children. Luisana and I have put our careers on hold in order to devote all our time and attention to helping Noah get well. At this difficult time, we ask only for your prayers and respect for our privacy.

"We have a long journey in front of us and hope that with the support of family, friends and fans around the world, we will win this battle, God willing."

According to reports, the boy was diagnosed after he and his mother travelled to the US due to health concerns.

The type of cancer he has has not been revealed.

Buble and Argentine model and actress Lopilato are also parents to nine-month-old son Elias.

During a recent appearance on ITV's Loose Women, 41-year-old Buble praised his children for giving him "perspective" and said that he was unaware how much he would enjoy being a father.

He said: "The only regret that I have in my life is that I took this long to have kids, because I had no idea the perspective it would give me.

"I had no idea how much I would love being a dad. That's it, that's all I care about... I love them too much probably, if there was such a thing.

"It's made everything else so insignificant, moments that I was afraid of and moments that would overwhelm me have now become a joy because I've realised how not serious they are compared to what is really important, which is Noah and Eli and that's it."

Buble and Lopilato married in 2011, before welcoming Noah in August 2013.

Buble was recently announced as the host of the annual Brit Awards ceremony in February 2017.

The Grammy Award-winning artist has also made several public appearances recently, including on an episode of Desert Island Discs and his own Buble At The BBC showcase.

In an interview earlier this year, 29-year-old Lopilato said she and her husband are "a little weird about our kids".

She told PageSix.com: "We love to be with our kids a lot. When we are out for one hour, we miss them."

Lopilato added that she and Buble do not work at the same time, and that she goes everywhere with her children.

In Buble At The BBC, the singer told host Claudia Winkleman he "just didn't know that level of love existed".

He said of his sons: "I just love them so much that part of loving them so much is not giving them everything they want and that is a tough thing for me."

When asked about returning to work, he said it was "really tough", and that Noah did not want him to leave.

He said: "My son Noah is three, Eli eight months, and Noah said to me 'Poppy, for what are you going?' I said 'Well, daddy is going to go and sing'.

"And it kills you, he said 'Please don't go, I will be a good boy', and I think I'm the worst human being in the universe."